Supplementary Figure 1: Chronic social defeat increases both neuronal excitability of the VTA DA system and DA levels in the NAc in susceptible but not in resilient mice.
From: Resilience to chronic stress is mediated by noradrenergic regulation of dopamine neurons
(a) Time (s) in the corner zone (F(2,73)= 24.8, p<0.001) was significantly increased during the second phase in the presence of CD1 mice (target) compared to the first phase with no target in susceptible mice (post-hoc ***p<0 .001). The time (s) spent in the corner zone with target was significantly increased in susceptible mice (n=29) compared with both control (n=30) and resilient mice (n=17) (post-hoc ***p<0.001). (b) Criterion of action potential waveform specific to a DA neuron (blue) with a long duration (>2.0ms) and a width form start to negative through > 1.1 ms compared to a non-DA neuron action potential (red). (c) Characteristics of a VTA-DA neuron burst activity with a burst starting with a latency between two action potentials <80ms and ended with a latency between two action potentials >160ms. (d) Example of recording track into the VTA. (e) Representative trace of pharmacological characterization of a VTA-DA neuron. (f) Sample traces for in vivo recording of VTA-DA neurons in control, susceptible and resilient mice. (g) The firing rate (Hz ; F(2,98)= 4.95, p=0.009 ; post-hoc *p=0.042, **p=0.0025 ; right), the number of bursts per minute (F(2,98)= 7.04, p=0.0014 ; post-hoc **p=0.0033, ***p=0.0007 ; middle) and the percentage of spikes within burst (%SWB ; F(2,98)= 3.68, p=0.029 ; post-hoc *p<0.05 ; right) was significantly increased in susceptible mice (n=32) to social defeat compared with both control mice (n=34) and resilient mice (n=35). (h) The level of DA (µg/g) in the NAc (H(2, 20)=3.65, p=0.44 ; right), but not in the PFC (F(2, 20)=0.89, p=0.42 ; left), was significantly decreased in resilient mice (n=8) compared with susceptible mice (n=7) (control mice n=9; post-hoc *p=0.014).
